Saccharides are chemical compounds which are found in many naturally-occurring substances. Included among these compounds are various sugars and carbohydrates. Among the sugars are found monosaccharides, disaccharides and polysaccharides. While the sugars themselves, including monosaccharides such as glucose, mannose, galactose, talose, fructose, allose, altrose, idose, gulose, xylose, lyxose, ribose, arabinose, threose, erythrose, etc., disaccharides such as maltose, cellobiose, sucrose, lactose, etc., or polysaccharides such as starch, cellulose, etc., are important chemical compounds, the hydrogenated products which may be obtained by hydrogenating said compounds are also important. For example, sorbitol, which may be obtained by hydrogenating glucose, will find a wide variety of uses such as in the manufacture of explosives, use in the synthesis of ascorbic acid, etc. or in solution form as an additive for cosmetic creams and lotions and toothpaste, tobacco, etc., as a bodying agent for paper, textiles, and liquid pharmaceuticals such as syrups, elixirs, etc., in the synthesis of resins, surface active agents, varnishes, etc. Likewise, mannitol, which may be obtained from fructose, will find various uses such as a base for tableting, as an ingredient in electrolytic condensers, as a basis of dietetic sweets, etc.
In hydrogenating these saccharides, it is an advantage to conduct the hydrogenation in an aqueous media due to the solubility of the saccharides in water with a concurrent generally insolubility in most organic solvents. The hydrogenation of these saccharides is usually accomplished using a metal hydrogenation catalyst, preferably one in which the metal is dispersed on a support. However, limitations on such metal catalyst composites have been found due to the lack of hydrothermal stability of the commonly used supports. This lack of stability exhibits disadvantages in that the lifetime of the catalyst is generally limited as well as providing the necessity for subsequent operation steps to remove any extraneous material which may be present in the reaction product due to the dissolved support material contained therein. This is particularly true when using traditional support materials such as the various aluminas and silica.
As will hereinafter be shown in greater detail, it has now been discovered that saccharides may be successfully hydrogenated utilizing a catalyst in which the catalytically active metal is composited on a particular type of support, said support being hydrothermally stable to the reaction conditions employed for the hydrogenation process.